How to season a steak?

I bought two 8oz Black Angus fillet Mignon steaks for my wife and I on
Valentines day from the local Giant supermarket. I seasoned the steaks
with our house seasonings which consists of garlic powder, onion powder,
pepper, and salt. Since it's cold where we're at, I cooked them in one of
those frying pans with the serrated bottoms. I cooked them in a couple of
pats of butter, until they were medium. They were tender, but I thought
the flavor was somewhat lacking. I know they will never compare to some
of the aged steaks I get at some of my favorite restaurants. But what can
be done to make a supermarket steak more flavorful? I know some
restaurants use a combination of spices to enhance the flavor.

-Thanks

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